<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>Jquery</title>
    <script type="text/javascript" src="js/jquery-1.7.1.min.js"></script>
    <script type="text/javascript">
		$(document).ready(function(){
			$('#agree').change(function(){
				state = $(this).attr('checked');
				if(state == 'checked'){
					$('#continue').removeAttr('disabled');
				}else {
					$('#continue').attr('disabled','disabled');
				}
			})
		});
    </script>
</head>
<body>
	<p>
    	<input id="agree" type="checkbox"/>I Agree
    </p>
    <input id="continue" type="button" value="Continue" disabled="disabled" />
</body>
</html>
